Railroad cars are commonly connected to each other via a coupling rod. Since small, substantially constant adjustments in the alignment of a railroad track are made upward or downward with regard to a vertical direction, the play of the coupling rod in the individual coupling organs of the train suffices to control the stresses between the individual railroad cars. The same applies when the train is driven around a curve. Consequently, neither tensile or compression forces are exerted through the coupling rod onto the following car, and instead these forces may be dampened through the dead weight of the railroad cars and transferred to the abutment between the cars.
While this may be true for railroad cars, the conditions are entirely different with respect to cableway cars, in particular with respect to suspension cableways, where the rails are laid out practically in a chain line. In such systems, two adjacent suspension cableway cars connected to each other through a coupling rod require a greater motion play than normal railroad cars. Added to this is the fact that the vibration stress from the cable as well as stress from other sources (such as wind) must not be increased through the use of a coupling rod. In addition, the problem of potential overload must be addressed in the development stage of a cableway system (similar to a railroad train). This is especially true with cableway cars due to their extremely light construction. Thus, a rigid coupling rod connecting two cableway cars is unsatisfactory.
In addition to the above-mentioned problems, sudden changes of direction of the suspension cable on or at supports may cause cableway cars to experience lift-up phenomena between the individual cars. Such lift-up phenomena increase the danger of derailing and/or causes significant operation disturbances.
From the "Internat. Seilbahnrundschau" No. 3/1989, page 32, a bent coupling rod having a hinged support for frequency increase is known. The bent coupling rod opposes an increase of the cableway speed due to the lack of an automatic vibration absorption.